| IFI Limited | Professional & scientific | 1983 |
| Ifunction Limited | Professional & scientific | 2011 |
| IG & SG Holdings Limited | Financial services | 2024 |
| IG Event Management Ltd. | Hospitality | 2017 |
| IG Khan Investment Ltd | Construction | 2021 |
| Ig&J Homes Ltd | Real estate | 2026 |
| Igcf Ltd | Transport & logistics | 2024 |
| Igea Limited | Wholesale & retail | 2024 |
| Igix Ltd | Transport & logistics | 2017 |
| IGL Care Ltd | Administrative & support | 2026 |
| IGL Logistics Ltd | Transport & logistics | 2026 |
| IGL Recovery Ltd | Water & waste | 2026 |
| IGL Transport Ltd | Transport & logistics | 2025 |
| IGM Automated Entrances Limited | Construction | 2011 |
| Igni Transport Ltd | Transport & logistics | 2018 |
| Ignite Hubs International Ltd | Administrative & support | 2017 |
| Ignite Investments Ltd | Real estate | 2020 |
| Ignite Live Network Limited | Professional & scientific | 2026 |
| Ignite Property Training Ltd | Administrative & support | 2023 |
| Ignite Recruit and Training Ltd | Administrative & support | 2025 |
| IGS E-Tronics Ltd | Manufacturing | 2020 |
| Iguana Blue Limited | Information & communication | 2017 |
| Igwt Accountants Ltd | Professional & scientific | 2023 |
| IH Fruit & VEG Ltd | Wholesale & retail | 2024 |
| IHA Real Estates Ltd | Real estate | 2025 |
| Ihbig Developments Ltd | Construction | 2026 |
| Iiotlink Ltd | Professional & scientific | 2019 |
| IJ Enterprise Ltd | Wholesale & retail | 2019 |
| Ijada Health Care Limited | Health & social care | 2018 |
| Ijas Business Development Limited | Administrative & support | 2017 |
| IJL Comms Limited | Information & communication | 2025 |
| IK Bus-Transport Ltd | Transport & logistics | 2023 |
| IK Novacart Ltd | Wholesale & retail | 2026 |
| IK Trans Ltd | Transport & logistics | 2016 |
| Ikek City Developments Limited | Construction | 2021 |
| Ikek Property Investment LLP | | 2023 |
| Ikester Property Holdings Ltd | Real estate | 2019 |
| Ikhide Foundation | Education | 2021 |
| ILA Developments Limited | Administrative & support | 2011 |
| Ilahi Group Ltd | Financial services | 2025 |
| ILB Parts Ltd | Manufacturing | 2025 |
| Ilex Homes (Drayton) Ltd | Construction | 2023 |
| Ilex Homes Ltd | Construction | 2021 |
| Illumiify Ltd | Wholesale & retail | 2025 |
| Illuminate Housing Limited | Real estate | 2021 |
| Illumino Ignis Holdings Limited | Financial services | 2022 |
| Illusioneering Limited | Professional & scientific | 2015 |
| Ilmore Ltd | Information & communication | 2025 |
| Ilumi Electrical Limited | Construction | 2026 |
| Iluminis (U.K.) Limited | Professional & scientific | 2005 |
| Ilyas Investments Ltd | Financial services | 2025 |
| IM Consultancy Services Ltd | Information & communication | 2015 |
| Image Design Solutions Limited | Professional & scientific | 2016 |
| Image Hair Salons Limited | Other services | 2005 |
| IMAGE5 Ltd | Professional & scientific | 2025 |
| IMAGENATION54 CIC | Information & communication | 2025 |
| Imagro TXF UK Ltd | Financial services | 2025 |
| Imagro UK Ltd | Wholesale & retail | 2009 |
| Imani Trading Limited | Wholesale & retail | 2026 |
| Imartins Engineering Limited | Construction | 2023 |
| Imatica Limited | Wholesale & retail | 2014 |
| Imbat Property Solutions Ltd | Real estate | 2025 |
| Imdad Network Ltd. | Professional & scientific | 2022 |
| Imhotep Limited | Transport & logistics | 2013 |
| IMK Trailers Ltd | Administrative & support | 2025 |
| IML Consulting (UK) Limited | Professional & scientific | 2014 |
| Immersiv Media Ltd | Information & communication | 2026 |
| Immigrant Writer Ltd | Professional & scientific | 2022 |
| Immigration Advice Consultancy Ltd | Professional & scientific | 2022 |
| Immink Transport Limited | Transport & logistics | 2025 |
| IMN Nutrition & Lifestyle Global Ltd | Other services | 2025 |
| Imodev Solutions Ltd | Information & communication | 2023 |
| Imol Preclinical Services Limited | Professional & scientific | 2008 |
| Impact Autism Consultancy & Training Ltd | Education | 2024 |
| Impact Connection Ltd | Information & communication | 2015 |
| Impact Financial Services Limited | Financial services | 2024 |
| Impact Global Coaching Limited | Information & communication | 2023 |
| Impact Investments Property Ltd | Real estate | 2023 |
| Impactdr Ltd | Administrative & support | 2017 |
| Imperial Cars (Cambs) Ltd | Wholesale & retail | 2025 |
| Imperial Dove Ltd | Real estate | 2022 |
| Imperial Real Estate Group Limited | Financial services | 2016 |
| Imperial Real Estate Holdings Limited | Financial services | 2016 |
| Imperial Standard 2 Limited | Real estate | 2022 |
| Imperial Standard Limited | Real estate | 2016 |
| Imperial Wood Limited | Real estate | 2016 |
| Imperium Automation Group Ltd | Financial services | 2023 |
| Imperium Automation Ltd | Manufacturing | 2020 |
| Imperium Capital Group Limited | Financial services | 2025 |
| Imperium Holdings and Management Ltd | Real estate | 2020 |
| Imperium Recruitment Ltd | Administrative & support | 2023 |
| Implants and Aesthetics Ltd | Health & social care | 2017 |
| Impra Charge Ltd | Construction | 2020 |
| Impressive Property Solutions LLP | | 2024 |
| Impulse Academy Limited | Arts & recreation | 2016 |
| Impulso Ltd | Wholesale & retail | 2026 |
| Imraf Ltd | Construction | 2024 |
| IMS Data Intelligence Ltd. | Administrative & support | 2017 |
| IMT Transport Limited | Transport & logistics | 2024 |
| IN Desserts Ltd | Hospitality | 2023 |